1. Field of Invention
The invention relates to an inductor and a manufacturing method thereof. In particular, the invention relates to an embedded inductor and the manufacturing method thereof.
2. Related Art
Technical progresses push electronic products toward the trend of miniaturization, low operating voltages and high operating currents. The basic and important elements such as the inductors are also requested to have lighter weight and smaller size in accordance with the miniaturization requirement.
As shown in FIG. 1, the conventional EI-type inductor 1 comprises an E-type iron core 10, a coil 11, and an I-type iron core 12 stacked in sequence. The two pins 11a and 11b of the coil 11 are correspondingly bent to two preformed recessions 12a and 12b of the I-type iron core 12, respectively.
However, since the inductor 1 consists of several independent components packaged together, there are many air gaps inside it. The air gaps will lower the operating efficiency of the element and are not suitable for the miniaturization of the element. To provide an inductor that has the characteristic of large currents, high frequencies and low magnetic loss, the embedded inductor is introduced. As shown in FIG. 2, U.S. Pat. No. 6,204,744 discloses a manufacturing method of an embedded inductor including the following steps 81 to 89. In step 81, one end of a coil is soldered to a corresponding pin frame. In step 82, the coil is wound. In step 83, the other end of the coil is soldered onto the pin frame. In step 84, the acetone solution is added. In step 85, the coil is fixed. In step 86, magnetic powders are formed by mixing first iron powders 861, second iron powders 862, a filler agent 863, a resin 864 and a lubricant 865. In step 87, a mold is provided to perform a die casting process with the magnetic powders. In step 88, the resin is cured by heating. In step 89, the pins are cut and bent.
U.S. Pat. No. 6,661,328 discloses another manufacturing method of an embedded inductor (not shown). The method includes the following steps. First, a mixture containing metal magnetic powders and resin is provided. The mixture is heated at a temperature between 65° C. and 200° C. Then, the mixture is granulated. The mixture is then die-casted to form a magnetic body that covers a coil. Finally, the magnetic body is heated to cure the resin.
The related art employs the die casting and thermal curing method on magnetic powders to form the embedded inductor. However, this technique is not only slow in production, but it also cannot meet the miniaturization requirement due to some technical problems. Therefore, these methods are not ideal for manufacturing compact inductors.
Therefore, it is an important subject to provide an embedded inductor, which has high operating efficiency and low magnetic loss, and can meet the miniaturization and high production rate requirements, and a manufacturing method thereof.